In a clear and dramatic break with the Bush doctrine of unilateral action, U.S. President Barack Obama pledged a "new era of engagement" with the world Wednesday, an appeal aimed at winning co-operation in dealing with vexing security issues such as containing Iran's nuclear ambitions.
Wielding both rhetorical carrot and stick, Mr. Obama used his first official address to the United Nations General Assembly to outline a vision of collective action across a range of issues, from terrorism to global warming.
"Those who used to chastise America for acting alone in the world cannot now stand by and wait for America to solve the world's problems alone. We have sought - in word and deed - a new era of engagement with the world. And now is the time for all of us to take our share of responsibility for a global response to global challenges," he said.
Building on themes articulated in his presidential campaign and developed in the first nine months of his administration, the doctrine outlined by Mr. Obama promised international co-operation with others, but insisted the United States gets a quid pro quo on key concerns, including some of the same ones pressed by his predecessor George W. Bush: international terrorists and preventing their safe haven in Afghanistan, and Iran's nuclear ambitions.
The speech garnered warm applause, and sent a buzz through a UN building packed with government leaders and foreign ministers.
"Everybody was very energized by the speech," Canadian Foreign Affairs Minister Lawrence Cannon said.
"North Korea and Iran are the two underlying issues in all this. Iran is probably more acute," said Bruce Jones, a scholar with the Washington-based Brookings Institution, whose work on building a new international order to promote security has clearly been influential in the Obama administration.
"A large part of the diplomacy - not just the speech, but the diplomacy - is to try to create the conditions for an effective coalition to deal with Iran, one way or another."
The Obama diplomacy starts from an understanding that the United States is the most powerful country in the world, but unable to accomplish crucial steps alone, Mr. Jones said. "So the U.S. is indispensable, but insufficient."
Iranian President Mahmoud Ahmadinejad was in the audience as Mr. Obama laid out fears that the nuclear-weapons ambitions of Iran and North Korea could send the world into regional crises and war.
"In their actions to date, the governments of North Korea and Iran have threatened to take us down this dangerous slope," he said.
Mr. Obama knows the United States alone cannot persuade or cajole Iran into abandoning its nuclear weapons, and the pressure for war, either through Israeli bombing or a U.S.-led campaign, could become irresistible. Countries such as Russia and China, if they agree to work in concert with the United States, could help to prevent such a confrontation.
Mr. Ahmadinejad's presence sparked controversy when the Canadian delegation, and those of a number of other countries, walked out during the Iranian President's speech, to protest his past attacks on Israel and his denial of the holocaust.
Mr. Obama's speech, however, was clearly designed to tell world leaders the United States is breaking with Mr. Bush's era of unilateralism, and it follows on a stream of calls for rebuilding U.S. diplomacy.
Mr. Obama opened by listing some of his administration's breaks with the past, such as his decree ordering the closing of Guantanamo Bay and his prohibition on U.S. government agents using torture, as well as his willingness to take action on climate change and to seek reductions of nuclear weapons and a treaty banning nuclear tests.
He outlined four pillars of international co-operation: preventing nuclear proliferation and working toward nuclear disarmament; promoting peace and combatting terrorism; preserving the planet; and building an equitable and growing global economy.
The speech has been accompanied by an unparalleled week of multilateralism by a U.S. president.
Mr. Obama spoke to a UN summit on climate change on Tuesday, addressed the UN General Assembly Wednesday, and will Thursday become the first U.S. president to personally chair the UN Security Council - for a meeting on nuclear non-proliferation and disarmament. Members are expected to approve a resolution toughening non-proliferation rules. Then Mr. Obama heads to Pittsburgh to host a summit of G20 leaders.
Mr. Obama, engaged in bruising domestic debates on issues such as health care, is now more popular abroad than at home. But many countries - the potential partners he seeks - are still uncertain whether he is outlining a lasting direction for the United States, or whether the country will revert to unilateralism.
Mr. Jones, the influential scholar, suggested Mr. Obama needs some domestic wins, such as getting Senate backing on a nuclear-test-ban treaty, to persuade doubters in foreign capitals.